How do i convert this equation into the node editor?
Labelled  'Layout > Reroute' nodelets not necessary, but often helpful.

Alternatively, if you have complex expressions to convert, you might consider using @Rich Sedman's Node-Expressions add-on, which could generate a group like this:



It's best to be quite explicit with your bracketing.. In this example, when I didn't bracket the unary minus on x, the negative was applied to the whole expression, rather than binding to the variable. This is expected Python.. but maybe not obvious.